1. Field of the Invention
The present document relates to a channel switch control method in a digital multimedia broadcasting receiver configured to disable the digital multimedia broadcasting receiver from operating against a channel switch command inputted before a screen output operation finish relative to an erstwhile channel, thereby enabling the digital multimedia broadcasting receiver that consumes a relatively large amount of time for channel switch to operate stably.
2. Description of the Related Art
Typically, a Digital Multimedia Broadcasting (DMB) denotes a new conceptual mobile multimedia broadcasting service combining broadcasting with communication. If mounted with a DMB receiving module, users can be provided with compact disk (CD)-quality sound and various high-level data via a mobile communication terminal, PDA (Personal Digital Assistant) or a vehicle-mounted terminal in transit or at a fixed place.
The DMB service uses as standard Digital Audio Broadcasting (DAB) system standardized from Eureka-147 (European Research Coordination Agency Project-147). The DMB service features multi-channel services and high quality sound, and diversified information can be provided therethrough. The DMB is largely divided into a terrestrial DMB and a satellite DMB according to method and network configurations.
The terrestrial digital broadcasting is largely divided into an American-type digital ATSC (Advanced Television Systems Committee) system using 8-VSB (Vestigial Side Band) modulation method and a DVB-T (Digital Video Broadcasting-Terrestrial) system using OFDM (Orthogonal Frequency Division Multiplexing) modulation method according to transmission method.
The American method is based on NTSC (National Television System Committee) frequency band and is convenient and economically excellent in embodying transmitter and receiver, and a high data transmission rate in a same bandwidth, but is inadequate for DMB that is intended for mobile reception because of weak in multiple interference path.
Accordingly, the terrestrial DMB adopts the European method that has an excellent mobile reception. Although the European method has a disadvantage compared with the American method in that it has a less amount of transmission data than that of the American method in the same bandwidth, but it has an advantage in that it is possible in mobile reception and a strong reception performance that is robust against the multiple interference path. However, a disadvantage is that it is difficult to simultaneously achieve high definition broadcasting and mobile reception at the same time in a frequency band of 6 MHz of each channel under the Korean situation.
The terrestrial DMB service launched in Korea as from Dec. 1, 2005 is embodied in such a manner that a channel is divided into 3 frequency blocks, whereby 3 DMB providers can be selected. Furthermore, it is stipulated that a provider divides for use the allocated frequency block into a TV broadcasting channel, 3 radio broadcasting channels and 1 data broadcasting channel. Consequently, in order to transmit a plurality of mutually different contents within the same frequency band, the same frequency band is so allocated as not to be time-duplicated, and plural contents are multiplexedly transmitted within the allocated time slot.
In a receiver receiving a signal transmitted by time division thus explained, specified contents wanted by a user out of the plural contents received via a frequency band are separated. Furthermore, the separated specified contents are accumulated up to a predetermined amount and receipt state thereof is discriminated. If the receipt state is discriminated as satisfactory, the received signal should be decoded and outputted such that it takes a lot of time to output contents corresponding to the channel selected by the user.
In other words, it is estimated that it takes approximately 2 seconds for a terrestrial DMB receiver to receive and output contents wanted by a user corresponding to a channel switch command. In the consumed time, it is estimated that it takes approximately 1.2 seconds for tuning of a tuner and decoding of a channel decoder to be performed, which is a longer interval than is typically spent by a user swiftly pressing a channel switch key via a remotely controller. In case of a terrestrial DMB receiver, contents corresponding to a channel switched in real time in response to a channel switch command cannot be outputted.
In consideration of characteristics of the terrestrial DMB receiver that cannot respond in real time to the channel switch command, the DMB system may operate unstably if a channel switch command is re-inputted before a screen output operation is completed relative to an erstwhile selected channel.